Q Could you explain the clutch stop, referred to in the
Page 65
If you've noticed an error in this article please click here to report it so we can fix it.
road test of the Foden eight-wheeler tested by your journal recently?
A The reference to a clutch stop in the
Foden test concerned a device which always used to be fitted on vehicles with heavy engines but which currently is only used on Foden and some machines equipped with David Brown gearboxes.
The device is a small disc or band-type brake which functions in the following manner: linked to the clutch-pedal through a spring loaded rod the brake is applied only on the last inch of pedal's travel. The brake-pad bears on a disc or drum slowing the clutch and spigot shaft mass. When a gearchange is being made, or when engaging a gear when the vehicle is stationary, the clutch and spigot shaft mass must be slowed or stopped from spinning before the gearbox dogs can be en gaged. The use of the stop when gear changing on the move is now largely superseded by the provision of synchromesh units which automatically adjust the speeds of the mating components within the gearbox so that they mesh quietly. Although a crash or constant mesh mechanism permits perfect gear changes to be made without clashing, the driver must wait until the momentum of the clutch and engine dies down to a speed at which the ratios will synchronize. The clutch stop is a brake which speeds up the die-down process.